1. Field of the Invention
The present invention relates to a method and a device for maintaining a predetermined voltage in a battery-supported vehicle electrical system.
2. Description of the Related Art
An internal combustion engine of a motor vehicle is generally started with the aid of an electrical starter. The power required for operating the starter is withdrawn from a battery of the vehicle electrical system of the motor vehicle. A vehicle system voltage may drop so much due to the load of the battery by the starter during the starting procedure that other consumers in the vehicle electrical system are not supplied with sufficient voltage. In particular, a consumer controlled by a microprocessor may react sensitively to an excessively low vehicle system voltage and may not function or may only function restrictedly for a predetermined time span. The consumer may be a control unit which is relevant for the operation and/or the safety of the motor vehicle.
If the motor vehicle is equipped with a start-stop mechanism, which already shuts down the internal combustion engine during a short stop and only restarts it when needed, starting procedures may be relatively frequent during travel of the motor vehicle and temporary failures of a consumer may be particularly serious. The present invention is therefore based on the object of providing a method and a device for ensuring a predetermined vehicle system voltage during a starting procedure.